The study covered in this summary was published in medRxiv as a preprint and has not yet been peer reviewed.

Key Takeaways

  • Transitions between metabolic health (no metabolic syndrome) and metabolic syndrome were relatively common in both directions across all body mass index (BMI) categories as adults aged from midlife to late-life in a Swedish study of 786 people.

  • As adults aged an average of 9.7 years (and up to 27 years) they commonly transitioned into worse weight and health categories, but 7% to 67% of participants transitioned from metabolic syndrome to metabolic health during follow-up.

Why This Matters

  • Understanding the transitions adults experience between various strata of BMI and metabolic health categories during long-term follow-up has been limited.

  • A better understanding of what predicts these transitions could substantially improve obesity care and help promote and maintain metabolic health.

Study Design

  • The study population consisted of 786 people drawn from the 859 individuals enrolled in the Swedish Adoption/Twin Study of Aging, which collected data serially from participants from 1986 to 2014.

  • Participants were classified as having normal weight (BMI, 18.5-24.9 kg/m2), overweight (BMI, 25-29.9 kg/m2), or obesity (BMI ≥ 30 kg/m2), and either being metabolically healthy (having no more than one of the following: hypertension, hyperglycemia, hypertriglyceridemia, and low high-density lipoprotein cholesterol; ie, no metabolic syndrome) or having metabolic syndrome, as defined by a 2009 consensus statement at midlife (age 50–64), early late-life (age 65–79), or later late-life (age ≥ 80).

  • The researchers identified changes in metabolic health status, study drop-out, and death.  

Key Results

  • At baseline, participants were a mean age of 65 years (range, 52-79 years) and 59% were women.

  • The proportions of metabolically unhealthy individuals and individuals with overweight or obesity increased over time.

  • Of the 100 individuals with values obtained both when they were 50-64 years old and ≥ 80 years old:

    • Of those who were metabolically healthy with normal weight, overweight, or obesity at midlife, 30%, 50%, and 67%, respectively, had transitioned to metabolic syndrome by late old age.

    • Of those with metabolic syndrome and normal weight, overweight, or obesity at midlife, 67%, 47%, and 25%, respectively, had transitioned to metabolic health by late old age.

  • Of the 382 individuals with values for ages 50-64 and 65-79:

    • Among those who were initially metabolically healthy, transitions to metabolic syndrome were more common in those with a higher BMI. The transition rates were 23% in normal-weight individuals, 38% in those who were overweight, and 43% in those with obesity.

    • Transitions in the opposite direction were relatively common among those with normal weight or overweight, with rates of 32% in normal-weight people, 42% among people who were overweight, and 7% among those with obesity.

    • Of the 262 individuals with values for ages 65-79 and ≥ 80 years:

      • Transitions from healthy to unhealthy categories were more common in obesity than other weight categories. The rates were 40% with normal weight, 39% with overweight, and 64% with obesity.

      • Transitions from metabolic syndrome to being metabolically healthy were more common in the lower BMI categories. The rates were 49% in normal-weight individuals, 24% among those with overweight, and 17% in those with obesity.

      • Drop-out rates among the six subgroups studied ranged from 17% to 23%, and mortality rates ranged from 19% to 34%.

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        Limitations

        • The sample was small.

        • The study cohort consisted of Swedish twins aged 50 and older who as a group at baseline had a relatively low prevalence of metabolic syndrome as well as relatively higher BMI, so the results may not be generalizable.

        Disclosures

        • The study did not receive commercial funding.

        • The authors report no relevant financial disclosures.

        This is a summary of a preprint research study, “Transitions between metabolically unhealthy and healthy obesity over 27 years from midlife to late-life,” by a senior researcher at the Karolinska Institute in Stockholm, Sweden and with coauthors from other centers in Sweden, China, and the United States. Preprints from medRxiv are provided to you by Medscape. This study has not yet been peer reviewed. The full text of the study can be found on https://www.medrxiv.org.

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